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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Chapter 29. Logical Replication</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="wal-internals.html" title="28.6. WAL Internals" /><link rel="next" href="logical-replication-publication.html" title="29.1. Publication" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">Chapter 29. Logical Replication</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="wal-internals.html" title="28.6. WAL Internals">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="admin.html" title="Part III. Server Administration">Up</a></td><th width="60%" align="center">Part III. Server Administration</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 18.0 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="logical-replication-publication.html" title="29.1. Publication">Next</a></td></tr></table><hr /></div><div class="chapter" id="LOGICAL-REPLICATION"><div class="titlepage"><div><div><h2 class="title">Chapter 29. Logical Replication</h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="sect1"><a href="logical-replication-publication.html">29.1. Publication</a></span></dt><dd><dl><dt><span class="sect2"><a href="logical-replication-publication.html#LOGICAL-REPLICATION-PUBLICATION-REPLICA-IDENTITY">29.1.1. Replica Identity</a></span></dt></dl></dd><dt><span class="sect1"><a href="logical-replication-subscription.html">29.2. Subscription</a></span></dt><dd><dl><dt><span class="sect2"><a href="logical-replication-subscription.html#LOGICAL-REPLICATION-SUBSCRIPTION-SLOT">29.2.1. Replication Slot Management</a></span></dt><dt><span class="sect2"><a href="logical-replication-subscription.html#LOGICAL-REPLICATION-SUBSCRIPTION-EXAMPLES">29.2.2. Examples: Set Up Logical Replication</a></span></dt><dt><span class="sect2"><a href="logical-replication-subscription.html#LOGICAL-REPLICATION-SUBSCRIPTION-EXAMPLES-DEFERRED-SLOT">29.2.3. Examples: Deferred Replication Slot Creation</a></span></dt></dl></dd><dt><span class="sect1"><a href="logical-replication-failover.html">29.3. Logical Replication Failover</a></span></dt><dt><span class="sect1"><a href="logical-replication-row-filter.html">29.4. Row Filters</a></span></dt><dd><dl><dt><span class="sect2"><a href="logical-replication-row-filter.html#LOGICAL-REPLICATION-ROW-FILTER-RULES">29.4.1. Row Filter Rules</a></span></dt><dt><span class="sect2"><a href="logical-replication-row-filter.html#LOGICAL-REPLICATION-ROW-FILTER-RESTRICTIONS">29.4.2. Expression Restrictions</a></span></dt><dt><span class="sect2"><a href="logical-replication-row-filter.html#LOGICAL-REPLICATION-ROW-FILTER-TRANSFORMATIONS">29.4.3. UPDATE Transformations</a></span></dt><dt><span class="sect2"><a href="logical-replication-row-filter.html#LOGICAL-REPLICATION-ROW-FILTER-PARTITIONED-TABLE">29.4.4. Partitioned Tables</a></span></dt><dt><span class="sect2"><a href="logical-replication-row-filter.html#LOGICAL-REPLICATION-ROW-FILTER-INITIAL-DATA-SYNC">29.4.5. Initial Data Synchronization</a></span></dt><dt><span class="sect2"><a href="logical-replication-row-filter.html#LOGICAL-REPLICATION-ROW-FILTER-COMBINING">29.4.6. Combining Multiple Row Filters</a></span></dt><dt><span class="sect2"><a href="logical-replication-row-filter.html#LOGICAL-REPLICATION-ROW-FILTER-EXAMPLES">29.4.7. Examples</a></span></dt></dl></dd><dt><span class="sect1"><a href="logical-replication-col-lists.html">29.5. Column Lists</a></span></dt><dd><dl><dt><span class="sect2"><a href="logical-replication-col-lists.html#LOGICAL-REPLICATION-COL-LIST-EXAMPLES">29.5.1. Examples</a></span></dt></dl></dd><dt><span class="sect1"><a href="logical-replication-gencols.html">29.6. Generated Column Replication</a></span></dt><dt><span class="sect1"><a href="logical-replication-conflicts.html">29.7. Conflicts</a></span></dt><dt><span class="sect1"><a href="logical-replication-restrictions.html">29.8. Restrictions</a></span></dt><dt><span class="sect1"><a href="logical-replication-architecture.html">29.9. Architecture</a></span></dt><dd><dl><dt><span class="sect2"><a href="logical-replication-architecture.html#LOGICAL-REPLICATION-SNAPSHOT">29.9.1. Initial Snapshot</a></span></dt></dl></dd><dt><span class="sect1"><a href="logical-replication-monitoring.html">29.10. Monitoring</a></span></dt><dt><span class="sect1"><a href="logical-replication-security.html">29.11. Security</a></span></dt><dt><span class="sect1"><a href="logical-replication-config.html">29.12. Configuration Settings</a></span></dt><dd><dl><dt><span class="sect2"><a href="logical-replication-config.html#LOGICAL-REPLICATION-CONFIG-PUBLISHER">29.12.1. Publishers</a></span></dt><dt><span class="sect2"><a href="logical-replication-config.html#LOGICAL-REPLICATION-CONFIG-SUBSCRIBER">29.12.2. Subscribers</a></span></dt></dl></dd><dt><span class="sect1"><a href="logical-replication-upgrade.html">29.13. Upgrade</a></span></dt><dd><dl><dt><span class="sect2"><a href="logical-replication-upgrade.html#PREPARE-PUBLISHER-UPGRADES">29.13.1. Prepare for Publisher Upgrades</a></span></dt><dt><span class="sect2"><a href="logical-replication-upgrade.html#PREPARE-SUBSCRIBER-UPGRADES">29.13.2. Prepare for Subscriber Upgrades</a></span></dt><dt><span class="sect2"><a href="logical-replication-upgrade.html#UPGRADING-LOGICAL-REPLICATION-CLUSTERS">29.13.3. Upgrading Logical Replication Clusters</a></span></dt></dl></dd><dt><span class="sect1"><a href="logical-replication-quick-setup.html">29.14. Quick Setup</a></span></dt></dl></div><p>
   3   Logical replication is a method of replicating data objects and their
   4   changes, based upon their replication identity (usually a primary key).  We
   5   use the term logical in contrast to physical replication, which uses exact
   6   block addresses and byte-by-byte replication.  PostgreSQL supports both
   7   mechanisms concurrently, see <a class="xref" href="high-availability.html" title="Chapter 26. High Availability, Load Balancing, and Replication">Chapter 26</a>.  Logical
   8   replication allows fine-grained control over both data replication and
   9   security.
  10  </p><p>
  11   Logical replication uses a <em class="firstterm">publish</em>
  12   and <em class="firstterm">subscribe</em> model with one or
  13   more <em class="firstterm">subscribers</em> subscribing to one or more
  14   <em class="firstterm">publications</em> on a <em class="firstterm">publisher</em>
  15   node.  Subscribers pull data from the publications they subscribe to and may
  16   subsequently re-publish data to allow cascading replication or more complex
  17   configurations.
  18  </p><p>
  19   When logical replication of a table typically starts, PostgreSQL takes
  20   a snapshot of the table's data on the publisher database and copies it
  21   to the subscriber.  Once complete, changes on the publisher since the
  22   initial copy are sent continually to the subscriber.  The subscriber
  23   applies the data in the same
  24   order as the publisher so that transactional consistency is guaranteed for
  25   publications within a single subscription.  This method of data replication
  26   is sometimes referred to as transactional replication.
  27  </p><p>
  28   The typical use-cases for logical replication are:
  29
  30   </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
  31      Sending incremental changes in a single database or a subset of a
  32      database to subscribers as they occur.
  33     </p></li><li class="listitem"><p>
  34      Firing triggers for individual changes as they arrive on the
  35      subscriber.
  36     </p></li><li class="listitem"><p>
  37      Consolidating multiple databases into a single one (for example for
  38      analytical purposes).
  39     </p></li><li class="listitem"><p>
  40      Replicating between different major versions of PostgreSQL.
  41     </p></li><li class="listitem"><p>
  42      Replicating between PostgreSQL instances on different platforms (for
  43      example Linux to Windows)
  44     </p></li><li class="listitem"><p>
  45      Giving access to replicated data to different groups of users.
  46     </p></li><li class="listitem"><p>
  47      Sharing a subset of the database between multiple databases.
  48     </p></li></ul></div><p>
  49  </p><p>
  50   The subscriber database behaves in the same way as any other PostgreSQL
  51   instance and can be used as a publisher for other databases by defining its
  52   own publications.  When the subscriber is treated as read-only by
  53   application, there will be no conflicts from a single subscription.  On the
  54   other hand, if there are other writes done either by an application or by other
  55   subscribers to the same set of tables, conflicts can arise.
  56  </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="wal-internals.html" title="28.6. WAL Internals">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="admin.html" title="Part III. Server Administration">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="logical-replication-publication.html" title="29.1. Publication">Next</a></td></tr><tr><td width="40%" align="left" valign="top">28.6. WAL Internals </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 18.0 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 29.1. Publication</td></tr></table></div></body></html>